The present invention pertains to a magnetic-field-producing therapy device for treating animal tissues with a time-varying magnetic field. Specifically, the therapy device of the instant invention generates a substantially only unipolar electro-magnetic pulse which assists a patient's bodily healing mechanism, thereby promoting faster healing of broken bones and enhancement of circulatory deficiencies.
The use of electrical energy to produce modifications in living tissue is well known. Electro-magnetic devices have been used to promote healing of broken bones. A. T. Barker, The Design of a Clinical Electro-Magnetic Bone Stimulator, Clinical Physical Physiology Measurement, February, 1981, Volume II, No. 1, Pages 9-16. Additionally, use of pulsed electro-magnetic fields (PEMF) to promote healing of bone tissue is described in U.S. Pat. No. 4,315,503 to Ryaby, et al. and in U.S. Pat No. 3,890,953 to Kraus, et al.
Use of electro-magnetic energy to arrest arthritic pain has been disclosed in U.S. Pat. No. 3,902,502 to Liss, et al.
A reading of the rather extensive literature in the field of electro-magnetic treatment teaches that there is little agreement amongst researchers in the field as to the most effective pulse wave form, frequency, and voltage level for treatment of tissue disorders. Without delving into the merits of one treatment method over the other, the present invention relates to an electro-magnetic-field-producing therapy device which generates a substantially rectangular, unipolar, electro-magnetic pulse of a predetermined frequency and amplitude and which includes a biasing means for preventing generation of a transient negative pulse when a positive, unipolar pulse collapses at the end of a duty cycle. The biasing means also substantially eliminates high frequency ringing at the beginning of a treatment pulse. A method of treating animal tissues with a time-varying, electro-magnetic field and apparatus for carrying out the method are taught. The method involves generating pulses in a frequency range of 1-100 hertz at an amplitude of 1-15 volts.
A basic premise of the teaching is that a negative pulse or spike which may form upon the collapse of a positive electro-magnetic field has a detrimental effect on the healing which is sought to be promoted by the application of the electro-magnetic pulse. Use of PEMF devices to promote vaso-constriction has not been successful due to the presence of high-frequency ringing at the beginning of a device duty cycle.
An object of the invention is to provide a method of treating animal tissue with a time-varying magnetic field, wherein the field is generated by a substantially rectangular, unipolar electro-magnetic pulse which is passed through a magnetic coil wherein the coil is biased to prevent the occurrence of a reverse polarity pulse upon the decay of the generated field.
Another object of the invention is to provide a device which will generate a magnetic field and which includes circuitry to prevent generation of a transient reverse polarity pulse upon the collapse of the generated field.
A further object of the invention is to provide a device which will be effective to form an electronic ice pack by acting as a vaso-constrictor.
In the preferred embodiment, a treatment pulse generator controls the frequency of magnetic pulses which are transmitted to a patient undergoing treatment. Circuitry is provided such that the initial frequency is ten times that of the ultimate treatment signal frequency, thereby allowing for substantially instantaneous adjustment of treatment signal frequency. This is particularly desirable when the device output is in very low frequency ranges, i.e. 0.1-20 hertz. A biasing circuit is provided in the device which induces an electrical current of the same polarity as the treatment signal through the treatment coils, thereby absorbing any reverse polarity spikes which may be generated simultaneously with collapse of the treatment signal generated field.
These and other objects and advantages of the instant invention and the method will become more fully apparent as the description which follows is read in conjunction with the drawings.